2. The Endosymbiotic Theory
Review:
What is a theory?
What is the difference between prokaryotic and
eukaryotic cells?
The endosymbiotic theory is the idea that a
long time ago, prokaryotic cells engulfed
other prokaryotic cells by endocytosis. This
resulted in the first eukaryotic cells.
First proposed by Lynn Margulis
Explains the origin of eukaryotic cells
Explains the origin of certain membrane-bound
organelles
3. What Exactly Happened?
Heterotrophic
bacteria
Ancient Prokaryotes
Ancient Heterotrophic
Prokaryote
Primitive Heterotrophic
Eukaryote
Primitive Autotrophic
(Photosynthetic) Eukaryote
Chloroplas
t
Photosynthetic
bacteria
Nuclear
envelope
evolving Mitochondrion
Plants and
plant-like
protists
Animals, fungi, and
animal-like protists
4. Membrane-Bound Organelles
Mitochondria =
membrane-bound
organelle that produces
energy for the cell
Chloroplast =
membrane-bound
organelle that captures
sunlight and uses it to
make food for the cell
5. Evidence in support of the
endosymbiotic theory:
Similarities between mitochondria,
chloroplasts, & prokaryotes:
1. Circular DNA
2. Ribosomes
3. Binary fission
6. Evidence in support of the
endosymbiotic theory:
Similarities between mitochondria,
chloroplasts, & prokaryotes:
1. Circular DNA
2. Ribosomes
3. Binary fission
